Flask



FIG. 1 is a front perspective view of a flask showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof; and,

FIG. 7 is a left side view thereof.

The dash-dot-dash broken lines of FIGS. 4 and 7 represent boundaries of the claimed design. All other broken lines illustrate portions of the flask that form no part of the claimed design. 

CLAIM The ornamental design for a flask, as shown and described. 